A variety of medical devices such as prostheses can be used to repair or replace damaged or diseased organs, tissues and other structures in humans and animals. Some of these medical devices incorporate tissue or synthetic material as at least a component of the prosthesis. Prostheses generally must be biocompatible due to possible prolonged contact with bodily fluids.
It is often necessary or desirable to treat the natural or synthetic tissue prior to use to improve performance of the prosthetic. Tissue used in prostheses typically is fixed prior to use. Fixation stabilizes the tissue, especially from enzymatic degradation, and reduces antigenicity.
In addition, a prosthesis can be treated with a variety of agents to reduce calcification, i.e., the deposit of calcium salts, particularly calcium phosphate (hydroxyapatite), following implantation in a recipient. Calcification affects the performance and structural integrity of medical devices constructed from these tissues, especially over extended periods of time. For example, calcification is the primary cause of clinical failure of bioprosthetic heart valves. The tissue can also be decellularized in an effort to reduce the effects of calcification and to promote cell growth. Other possible treatments include the application of, for example, antimicrobials, antioxidants and antithrombotics.
Some treatments for medical devices involve the use of potent chemicals, which can result in degradation of delicate portions of the medical device. Also, treatments beneficial to one portion of a medical device may be detrimental to another portion of the bioprosthesis. Furthermore, certain treatments may be appropriate for one portion of a medical device but not other portions due to differences in material or due to the different environments to which the different portions of the medical device may be exposed during use.